Content distribution via a distribution network and an access network

ABSTRACT

A method and apparatus for streaming content to an access network in an interactive information distribution system. The method encapsulates the content in accordance to an Internet Protocol (IP). The content is then transcoded into a format supported by the access network, and streamed over a distribution network to a remote server or to a subscriber terminal that is coupled to the access network. The apparatus is embodied as stream caching server for streaming the content encapsulated within the packet to access networks via a stream distribution network in response to a request for content. A packet processor is coupled to the stream server for processing the encapsulated content within the IP packets into a format native to the access network.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.14/848,204, filed Sep. 18, 2015, which is a U.S. patent application Ser.No. 11/618,347 (now U.S. Pat. No. 9,172,735), filed Dec. 29, 2006, whichis a continuation of U.S. patent application Ser. No. 09/772,287 (nowU.S. Pat. No. 7,159,235), filed on Jan. 29, 2001, which claims thebenefit of U.S. Provisional Patent Application Ser. Nos. 60/178,810,60/178,857, 60/178,795, and 60/178,809, all filed on Jan. 28, 2000. Eachof the above-mentioned applications is incorporated herein by referencein its entirety.

This application is related by subject matter to U.S. patent applicationSer. No. 09/772,288, filed on Jan. 29, 2001, which is incorporated byreference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to electronic data storage and transmission ofcontent or information. More particularly, the invention relates to amethod and apparatus for streaming content in an interactive informationdistribution system.

2. Description of the Background Art

Information systems such as video on demand (VOD) systems are capable ofstreaming a program content selection to a great number of users orsubscribers. To provide program content requested by a subscriber, avideo server retrieves the requested program content from a storagemedium and transmits the program content over a stream distributionnetwork to a local access network (e.g., a cable television network).The local access network supports a group or “neighborhood” ofsubscriber terminals, and downloads the program content to therequesting subscriber. The subscriber may then view the requestedprogram content at their subscriber terminal, display coupled to aset-top box, or any other subscriber equipment capable of extractingaudio, video, and data signals from the program content.

Various types of access networks have evolved and become standardized,such as the Internet, cable networks, LAN/WAN networks, digitalsubscriber lines DSL, satellite, and the like. Furthermore, each type ofnetwork requires specific transport data structures and protocols, aswell as having various limitations with respect to transmission latency,bandwidth, and the like. To service a wide subscriber base, the VODsystems currently implement different solutions for each type of accessnetwork. For example, VOD systems that provide web-based video contentalong public and private wide area networks require distribution ofcontent at a particular quality of service (QoS), e.g., bit rate, mediumlatency, low bandwidth, and lower grade quality video (e.g., higherjitter). Alternately, VOD systems that provide cable-based video alongcable networks require a quality of service having low latency, highbandwidth, and high quality video.

In order to accommodate multiple access networks, separate video serversare provided at a head-end for each type of access network. However,such a solution increases the cost of providing program content at thehead end, since more hardware is required. To reduce such costs andother deficiencies, there is a need in the art to provide a scalable VODsolution that is readily adapted to different types of access networks.

SUMMARY OF THE INVENTION

The invention provides a method and apparatus that is capable ofstreaming content to different types of access networks in aninteractive information distribution system. The method initiallyreceives content encapsulated in accordance to an Internet Protocol(IP). Tn one embodiment, the content is configured as a plurality ofpackets. e.g., MPEG-2 or MPEG-4, contained in a payload of a RealtimeTransport Protocol (RTP) packet within an IP packet. The content is thentranscoded into a format supported by a particular access network or aparticular subscriber terminal, and streamed over a distribution networkto a remote server or to a subscriber terminal that is coupled to theaccess network. The apparatus is embodied as a stream caching serverand, illustratively, a packet processor within the interactivedistribution system.

By streaming program content in a manner that is common for servicingvarious types of access networks and subscriber terminals, the presentinvention provides scalable streaming of content to cable plants,digital subscriber line (xDSL) plants, terrestrial distributionnetworks, satellite distribution networks, private networks, theInternet, and the like. The storage of the content in IP formatminimizes the amount of data conversion otherwise required to streamcontent between different types of networks. Additionally, the payloadof the RTP packet is sized as a read block to minimize latencies inretrieving and streaming content. That is, the storage media read blocksize conforms to the optimal buffer size units of the currentequalization of the stream servers. Furthermore, since the content isstored at the stream cache servers as IP packets, a communications(i.e., protocol) stack is not required at either the input or output ofthe distribution network.

BRIEF DESCRIPTION OF THE DRAWINGS

The teachings of the present invention can be readily understood byconsidering the following detailed description in conjunction with theaccompanying drawings, in which:

FIG. 1 depicts a high-level block diagram of an interactive informationdistribution system embodied in the present invention;

FIG. 2 depicts a high level block diagram of local and remote head-endsin the interactive information distribution system of FIG. 1;

FIG. 3A depicts one embodiment of an Internet Protocol (IP) packet usedin the present invention;

FIG. 3B depicts one embodiment of a Realtime Transport Packet (RTP)contained in a payload section of the IP packet of FIG. 3A;

FIG. 4 depicts a block diagram of a plurality of points of presence forproviding varying types of content;

FIG. 5 depicts a block diagram of a third embodiment of the inventionfor an Internet multimedia service;

FIG. 6 depicts a flow diagram of a method for responding to a userrequest for particular content over the system of FIG. 2

FIG. 7 depicts a flow diagram of a method of transferring the types ofcontent from the plurality of points of presence of FIG. 4.

To facilitate better understanding of the invention, identical referencenumerals have been used, where possible, to designate identical elementsthat are common to the figures.

DETAILED DESCRIPTION

The invention provides a method of distributing (i.e., streaming)packets of content (e.g., video-on-demand, pay-per-view, MP3, digitalbroadcast, or any other content that may be streamed) from a commondistribution source such as a video stream server, to various types ofaccess network domains (e.g., LAN/WAN, cable, digital subscriber line,satellite, terrestrial, and the like). In particular, the inventionallows for an extension of Internet protocols into traditionallynon-Internet networks, as well as use of existing commercial equipmentfor providing interactive streaming services. As such, the existingInternet backbone may be utilized to provide streaming services to thesevarious non-Internet networks.

FIG. 1 depicts a high-level block diagram of an interactive informationdistribution system 100. One exemplary distribution system 100 is forvideo-on-demand (VOD) is described in U.S. Pat. No. 6,253,375, andhereby incorporated herein by reference in its entirety. In such a VODsystem 100, a user may request and receive a particular contentselection, e.g., video, movie, or programming content from a serviceprovider without any time restrictions (e.g., time slots) such as thosenormally associated with cable and television programming.

The system 100 comprises a local head-end 101, one or more remotehead-ends 201 _(n), a stream distribution network 104, a plurality ofaccess networks 111 ₁ through 111 _(n) (collectively access networks111) and a plurality of subscriber equipment 115. The system 100 streamscontent from the stream caching server 102, where the content isformatted as Internet Protocol (IP) packets. Specifically, the contentis configured as a plurality of packets (e.g., MPEG packets) containedin a payload of a Realtime Transport Protocol (RTP) packet within an IPpacket. The use of this IP formatted content enables a single streamcaching server 102 located at the head-end to stream content over thestream distribution network 104 to either homogeneous or non-homogeneoustypes of access networks 111 in a format native to such access network111. As such, the system 100 is capable of streaming the same contentto, for example, a person utilizing cable service, a computer on theInternet, a DSL, satellite, and the like.

The stream distribution network 104 serves as the “backbone” structureof the network and may include multiple physical layers such assynchronous optical networks (SONET) and/or an asynchronous transfermode (ATM) type of network, as well as virtual private networks (VPN)over existing Internet backbones. As such, a plurality of local headends 101 may be remotely located from each other, where one or moreproviders, such as a long distance phone company, provides the streamdistribution network 104 connectivity therebetween.

Each local head-end 101 has a switch 142, which serves as an input tothe stream distribution network 104 when “downstreaming” content (i.e.,providing content toward subscribers), and an output for the streamdistribution network 104 when “upstreaming” requests or content (i.e.,receiving content or requests from subscribers). Furthermore, eachaccess network 111 is coupled to the stream distribution network 104 viaan interface such as data link converter 112. The data link converter112 serves as an output port for the stream distribution network 104when downstreaming content, and as an input port to the streamdistribution network 104 when upstreaming requests or content.

The local head end 101 comprises a stream caching server 102, aninfrastructure system manager 140, a switch 142, and a packet processor144 such as an MPEG packet processor. The stream caching server 102comprises a central processing unit (CPU) 146, a storage medium 148,memory (e.g., RAM) 150, and support circuits 154. The RAM 150 stores asoftware program 152 that is executed by the CPU 146 to implement thepresent invention. The CPU 146 executes the software program 152 tothereby coordinate the streaming of content to the distribution network104. The storage medium 148 stores the content that is streamed by thestream caching server 102. This content is stored as files according tothe IP protocol, that is, in IP packet form. One configuration of thestorage medium 148 is a redundant set of disk arrays, e.g., RedundantArray of Inexpensive Disks (RAID) where the IP packets of each file arestriped across the set of disks. The support circuits 154 provide aninterface for receiving system commands from the manager 140, streamingcontent to the distribution network 104, and the like.

The infrastructure system manager 140, having a controller and memory(shown in FIG. 4), coordinates a user request from the subscriberequipment 115 by passing the user request to the stream caching server102, and then establishing a session between the subscriber equipmentand the stream caching server 102.

The switch 142 is capable of routing, illustratively, MPEG and/or IPpackets. The switch 142 routes the user request from the streamdistribution network 104 to the system manager 140. Additionally, theswitch 142 routes the content from the stream caching server 102 to thepacket processor 144. The packet processor 144 provides preprocessingand post processing operations content. The preprocessing operationsperformed on the content, modify the content to a format and size thatcorresponds to or accommodates the characteristics of the stream server102. Raw content such as packet elementary streams of audio, video,data, and the like are provided by a service provider, video library andthe like to the local and remote head-ends 101 and 201 _(n). During thepreprocessing operation, the packet processor 144 transcodes (i.e.,decoding and then encoding) the content from one format to anotherformat as necessary, prior to storing the content on the storage medium148. Preferably the content is compressed as MPEG packets (e.g., MPEG-1,MPEG-2, or MPEG-4 packets) encapsulated in a portion of the payload ofan IP packet if not already received from the content provider in suchformat. In this manner, concurrent streams may be provided to multipleaccess networks 111 from a single copy stored on the storage medium 148

FIG. 3A depicts one embodiment of an Internet Protocol (IP) packet 300used in the present invention. The IP packet 300 comprises an IP header310 and an IP payload 320. The IP payload 320 comprises a UDP (UserDatagram Protocol) packet 321 having a UDP header 322 and a UDP payload324. The UDP payload 324 further comprises a Realtime Transport Packet(RTP) 330, a stream integrity check 326, and a cyclic redundancy check(CRC) 328. In one embodiment of the IP packet 300, the IP header 310 is20 bytes, the UDP header 322 is 8 bytes, the stream integrity checkfield 426 is 4 bytes and the CRC field 428 is 4 bytes.

FIG. 3B depicts one embodiment of a Realtime Transport Packet (RTP) 330encapsulated in a payload section 320 of the IP packet 300 of FIG. 3A.The RTP packet 330 comprises a RTP header 340 and a RTP payload 350. TheRTP payload 350 contains the actual packetized content (e.g., MPEG-2transport packets 352 through 356) containing the subject matter (e.g.,movie, audio, data, and the like) that a subscriber or user isinterested in retrieving. The format of the packetized content 352through 356 may be in the packetized format as received from the contentprovider, or transcoded during the preprocessing operation by the packetprocessor 144 into a format that accommodates the stream server 102. Inparticular, the number of content packets positioned in the RTP payloadis dependent on design limitations of the server components.Specifically, the IP packets are striped across an array of disks in thestorage medium 148 such that each respective data block or “extent”stored on a disk has a size corresponding to a predefined amount of IPpackets. The size of the read block is a multiple integer of the RTPpacket size. Furthermore, the RTP packet is sized to optimize the use ofa buffer in the packet processor 144, which has a specific memorycapacity (e.g., 1 Kbyte). As such, the RTP packet 330 is sized such thata multiple integer of RTP payloads 350 may be read by a read block tothereby minimize the latencies in retrieving and streaming content fromthe stream caching server 102 to the distribution network 104. For adetailed understanding of defining extent size for storing data streamshaving different bit rates, the reader is directed to U.S. Pat. No.6,282,207, which is hereby incorporated by reference herein in itsentirety.

For example, a read block for the packet processor 144 is sized to readMPEG-2 packets that are encapsulated in the payload of each RTP packet.Furthermore, the number of MPEG-2 packets in the RTP payload 350corresponds to the buffer space in the Fiber Channel controller (notshown) of the packet processor 144. Specifically, the buffer space inthe Fiber channel controller has buffer granularity for five MPEG-2packets. As such, five MPEG-2 packets 352 through 356 are illustrativelyshown in the RTP payload 350. Accordingly, the content is configured asa plurality of packets contained in a payload 350 of a RTP packet 330,wherein the RTP packet 330 resides within the payload 320 of the IPpacket 300. The RTP format (RFC 1889) minimizes the latency in streamingcontent from the server by supporting the streaming of content in realtime.

After a user request is received from a user or subscriber of serviceslocated at a particular access network, the packet processor 144 iscapable of post processing the stored content into a format thatconforms to the particular access network from which the request forcontent originated. Post processing by the MPEG processor 144 includessizing (e.g., “grooming”) and optionally transcoding the underlyingcontent located in the IP payload into a format native to the accessnetwork 111 of the requester. That is, the underlying packet structureis adapted to the requester's access network, while the encapsulating IPpacket structure is used to deliver the modified or unmodifiedunderlying packet structure to the access network via the distributionnetwork (IP “backbone”) 104.

Transcoding of the underlying content (e.g., MPEG transport packets 252to 256) in the RTP payload 350 of the packets is performed toaccommodate transfer over the particular access network 111 from wherethe request for content originated. The packet processor 144 transcodesthe content without disturbing the overall IP format of the packet(i.e., header information), since the IP format is required to transferthe entire packet over the stream distribution network 104. The packetprocessor 144 illustratively extracts the 5 MPEG packets 352 through 356from the IP, UDP, and RTP header information 310, 322, and 340respectively, and transcodes the MPEG packets 352 through 356 into aformat supported by the access network 111 where the request for suchcontent originated. The transcoding is performed by decoding theunderlying content in its original packet format (e.g., MPEG-2 packets),and then encoding the decoded content into a new packet format. As such,the transcoding may change the rate of the content. For example, thetranscoding may include the conversion of MPEG-2 formatted content intoMPEG-1, AVI, MPEG-4, Moving JPEG, windows media, real video formatcontent, and the like. Furthermore, the number of packets in the RTPpayload 350 may be illustratively changed (e.g., 5 MPEG-2 packets into 4MPEG-4 packets.

The transcoding is performed in accordance to an extended Real TimeStreaming Protocol (RTSP-RFC 2326) such that stream manipulationsconform to Internet standards and are applicable to any access network111 that supports an Internet protocol.

The packet processor 144 combines the transcoded packets with the IP,UDP, and RTP header information to recreate the IP packet. Furthermore,the content in the IP packet can be configured to maintain a specificlevel or range of Quality of Service (QoS). The quality of service tothe subscribers includes providing the necessary rate of streamingcontent (e.g., constant bit rate (CBR) or variable bit rate (VBR)) andtolerable jitter over a specific bandwidth to the subscribers.Accordingly, other functions performed by the MPEG processor 144 includejitter correction, creation of packet elementary streams (PES), streamsplicing, statistical multiplexing, and the like.

In one embodiment, the transcoding is performed by the MPEG processor144 prior to storing the content in IP packet form on the storage medium148. In particular, multiple copies of the content are stored in thevarious packet formats (e.g., MPEG-1, MPEG-4, AVI, MJPEG, and the like)on the storage medium 148 for subsequent distribution to a respectiveaccess network 111 as required. Alternately, in a second embodiment, thecontent is stored illustratively as MPEG-2 packets encapsulated in an IPpacket, and is subsequently transcoded “on the fly”, that is after theIP packets have been retrieved from the storage medium 148. In theformer embodiment, greater storage capacity is required, while in thelatter embodiment, greater processing capacity is required.

Furthermore, the transcoded IP packets are also sized at the head-end101 prior to distribution over the stream distribution network 104 for aplurality of 64QAM or 256QAM channels at the data link converters. Thedistribution network 104 carries groupings of streams that have beenadapted to the 64QAM or 256QAM channels to the data link converters(e.g., 112). Each data link converter comprises a plurality ofQuadrature Amplitude Modulation (e.g., 2-32) modulators (not shown). Inparticular, the packets are sized to carry additional informationpertaining to the underlying content (e.g., program system information(PSI) for MPEG type packets) at the head-end 101 as opposed to beinginserted downstream at the access network. Thus, processing for each QAMchannel is moved to the input of the distribution network 104, asopposed to the output (i.e., data link converter) of the distributionnetwork 104.

In the exemplary system 100 depicted in FIG. 1, three types of accessnetworks 111 are illustratively shown. Each access network 111 iscoupled to the distribution network 104 by the data link converter(e.g., 112, 118, and 126). The IP header 310 contains source anddestination addresses for delivering the IP packet. The source addressis the address of the stream cache server 102 and the destinationaddress is the address of the destination access network 111. Once theIP packet is received by the data link converter, the underlying content(e.g., MPEG packets 352-356) are transferred to the subscriber equipment115 of the requester. How the underlying content is transferred to theparticular subscriber equipment 115 is dependent on the type of accessnetwork as discussed below.

One type is a LAN/WAN network 106, which typically is a private networkor one provided by an Internet Service Provider (ISP). The physicallayer of the LAN/WAN may be 10 base T, 100Base Tx, Gigabyte Ethernet,10G Ethernet, 40G Ethernet, ATM, Frame Relay, and the like. A userconnected to a Local Area or Wide Area Network (LAN/WAN) 106 makes arequest for content from the subscriber equipment 115 such as a computerterminal 116. The request for content (e.g., video content) is modulatedby the modem 114 onto the LAN/WAN network to a data link converter 112.The data link converter 112 attaches IP packets to the user's requestsignal for upstream transport over the stream distribution network 104to the head-end 101. The switch 142 receives and routs the user requestto the infrastructure system manager 140 where the user request ischecked by the system manager 140 for proper user identification,billing, availability and permissions for the requested content, andother administrative functions. Upon allowing the user request, asession is established, whereby the system manager 140 sends a signal tothe stream caching server 102 to stream the selected video to the accessnetwork of the requester.

In particular, the stream caching server 102 retrieves the selectedvideo, which is stored as IP packets in the storage medium 148, androuts the IP packets to the MPEG processor 144 via the switch 142. In aninstance where the underlying payload content 350 that the userrequested is already in a format required by the access network 111,then the IP packets 300 containing the underlying payload content 350are routed to the data link converter 112 via the stream distributionnetwork 104. However, if the RTP payload portion 350 of the IP packets300 contain underlying content in a format that is not native to theaccess network 111 from where the request originated, then theunderlying packets in the RTP payload 350 are transcoded by the MPEGprocessor 144 into a format native to the LAN/WAN network 106 asdescribed above. The switch 142 then routs the transcoded IP packets 300over the stream distribution network 104 to a data link converter 112.

The data link converter 112 receives the routed IP packets from thestream distribution network 104 and extracts the underlying content inthe RTP payload 350 (whether transcoded or not) from the remainingportion of the TP packet 300. The data link converter 112 then modulatesthe extracted program content for transmission to the requester'ssubscriber equipment 115, such as a computer terminal 116. One exampleof a data link converter 112 is a DIVA Digital link (DDL 500)manufactured by DIVA Systems Inc. of Redwood City, Calif. The DDL 500may comprise a compact PCT-based assembly containing a set of circuitcards that provide communications between the subsystems in the head-end101 and the subscriber equipment 115 of the user (e.g., home, office,and the like). The data link converter comprises a controller card, oneor more Fiber Input boards (FIB), multiplexer boards, and a plurality ofQAM modulators. In general, the data link converter receives and sendsdata to and from the video switch. In-band content streams aretransferred from the FIB, through the Multiplexer, and to the QAMmodulators, which modulate the program content on individual QAM channelover the LAN/WAN 106 (e.g., Ethernet) network. A modem (e.g., modem114), coupled to the subscriber equipment 115, then demodulates videocontent and transfers the demodulated packets for processing and viewingat the subscriber equipment 115 (e.g., computer terminal 116).

FIG. 1 also depicts the inventive system 100 for a subscriber forservices (e.g., video-on-demand services), which is coupled to a digitalsubscriber line (DSL) access network 111 ₂. The DSL access network 111 ₂comprises the data link converter 118, a local carrier (e.g., T1, T3,and the like) 108, a digital subscriber line access multiplexer (DSLAM)119, a digital subscriber line modem 120(x-DSL modem, where “x”represents a specific type of DSL modem) and the subscriber equipment115 (e.g., computer terminal 122 or digital video recorder (DVR) 124).

A DSL subscriber also receives the requested program content in asimilar manner as described with regard to the LAN/WAN access network106. Specifically, the server 102 streams content via the streamdistribution network 104 to a data link converter 118 that is designatedfor that particular subscriber. More specifically, the data linkconverter 118 receives the IP packets 300 from the distribution network104 and then extracts the underlying content packets from the RTPpayload 350. The underlying content packets may be in a format asoriginally stored on the storage medium 148 at the head-end 101 ortranscoded to a format required by the DSL access network 111 ₂ in thesame manner as previously discussed. The data link converter 118 thenconverts the extracted packets into a format pertaining to the carriernetwork 108 such as ATM, Ethernet, and the like. The newly convertedpackets containing the underlying content is then transferred by thedata link converter 118 to the DSLAM 119 over the local carrier (e.g.,T1 or T3 carrier lines) 108. The DSLAM 119 then multiplexes therequested content to the particular digital subscriber line modem 120(x-DSL modem, where “x” represents a specific type of DSL modem) of therequester for services.

For real time information distribution, the xDSL modem 120 is a VDSL(Very high data rate Digital Subscriber Line). However, where thepresentation of information does not have to be in real time, but may bea delayed presentation, then the xDSL modem 120 may be a ADSL(asynchronous DSL) modem, HDSL (high bit rate DSL) modem, or SDSL(synchronous DSL) modem, and the like. Such lower speed DSL modems aretypically used during non-peak hours.

The x-DSL modem demodulates the content for processing and viewing atthe subscriber equipment 115 (e.g., the computer terminal 122 or adisplay device (not shown) coupled to the DVR 124). Furthermore, asubscriber request for content or uploading content from the computerterminal 122 or set-top box (not shown) travels in the reverse pathtaken by the downstream content.

FIG. 1 also depicts a cable access network 111 ₃. In particular, system100 operates in a similar manner as described above with respect to theLAN/WAN or DSL access networks, except to format the content accordingto DOCSIS (data over cable service interface specifications) prior totransmission over the stream distribution network 104. Specifically, aDOCSIS media access control (MAC) layer 156 (drawn in phantom) islocated at the head-end 101 before the stream distribution network 104.DOCSIS takes the IP packets and encapsulates them into the payload of aMAC packet. The packet processor 144 then encapsulates the MAC packetinto the payload of an IP packet 300, such that an IP packet 300 carriesa MAC packet, which carries an IP packet 300 having MPEG packets. Assuch the conversion into the MAC format occurs at the head-end 101, asopposed to downstream at the access network 111 ₃. Furthermore, theswitch 142 treats the MAC packets encapsulated in the IP packet as anyother IP packet when distributing such IP packets over the distributionnetwork 104. Moreover, the data link converter 118 simply extracts theMPEG transport packets from the MAC packets in a similar manner asdiscussed above.

The IP packets 300 carrying the requested content are distributed overthe stream distribution network 104 and received by the data linkconverter 126, where illustratively, the MPEG packets 352 through 356 inthe MAC packet payload are modulated over the cable network (e.g.,hybrid fiber coax (HFC) 110 to the subscriber equipment 115.Specifically, the content is transmitted from the cable network 110 to aset top terminal 128 or a cable modem 130 that demodulates the programcontent for viewing on a computer terminal 132, display device coupledto the DVR 134 or the like. A request from a cable subscriber isprocessed via the cable network 110, the OOB (out of band) router 136,and the data link converter 126, which modulates the request back overthe stream distribution network 104 to the head-end 101.

Although the system 100 is illustratively shown to stream programcontent to the LAN/WAN 106, the local carriers 108, and the cablenetwork 110, the system 100 may also stream content to other types ofaccess networks. Additionally, each system 100 actually streams contentover many more access networks and subscriber terminals thanillustratively depicted in FIG. 1.

FIG. 4 depicts a block diagram of a plurality of points of presence(POP) for varying types of content. In particular, the system 400comprises local head-end 401 having a stream caching server for VOD 102₁, a stream caching server for advertisement insertion 102 ₂, a streamcaching server for Pay-Per-View 102 ₃, and other servers 102 _(p) suchas a chat server, e-mail server, http server, electronic program guideserver, and the like, all coupled to the switch 142. The remainingportions of FIG. 4 are the same as in FIG. 1, except only thedistribution network and one data link converter are shown forsimplicity.

The requester may select content from any point of presence (i.e.,server) containing information that is networked to the Internetbackbone. That is, as long as the packet processor 144 can groom andtranscode the underlying content packets in the IP packet 300 into aformat native to the access network from which the request originates,then the inventive distribution system 400 may retrieve data fromvirtually any type of information (i.e., content) distributed by aserver, whether the content is audio, video, data, voice, or otherwise.

FIG. 5 depicts a block diagram of a third embodiment of the inventionfor an Internet multimedia service 500. A head-end 501 is coupled to thestream distribution network 104 as discussed in FIGS. 1 and 2, as wellas the plurality of access networks 111 (only a data link converter,e.g. converter 126 of FIG. 1, of one access network 111 shown forsimplicity). The head-end 501 comprises a stream caching server 102, ahypertext transfer protocol (http) proxy server 502 for static hypertextmarkup language (HTML) pages, a http server 504 for dynamic HTML pages,the infrastructure system manager 140, and packet processor 144, whichare all coupled to the switch 142.

In this embodiment, the stream caching server 102, the http proxy serverfor static HTML pages 502, and the http server for dynamic HTML pages504 may be synchronized with the stream caching server 102 such that apresentation to a subscriber is a multimedia presentation where theviewer is illustratively streamed a movie or audio (via the streamcaching server 102) along with a web page (via the static and/or dynamichttp servers 502 and/or 504). Segmenting the network in this mannerpermits streaming of information over less than high quality servicechannels for information that does not require such high qualitystandards.

Since the stream server 102 is designed for streaming packets, while thehttp servers 502 and 504 are not, and the http servers 502 and 504 aredesigned for random access while the stream server 102 is not, thencombining the two types of servers into a single server would result inthrashing when retrieving and streaming content and underutilization ofthe single server. As such, providing separate http servers 502 and 504with the stream caching server 102 allows the network to designatebandwidth according to the type of information requested from theappropriate server, and then multiplex the streams of requestedinformation in the form of LP packets over the distribution network 104for subsequent distribution to the access network where the requestoriginated. In this manner, a requester on any access network III isseamlessly provided with various types of content from dedicated sourcessimultaneously, without interruptions due to latencies between each typeof source.

FIG. 2 depicts at least one remote head-end 201 ₁ (where head-end 201_(n) is drawn in phantom) coupled to the interactive informationdistribution system 100 of FIG. 1. Each remote head-end 201 of thesystem 100 comprises a stream caching server 202, an infrastructuresystem manager 204, switch 242, and other hardware and softwarecomponents as described above with regard to the local head 101. Eachremote head-end 201 is coupled to the stream distribution network 104via its respective switch 242.

When the local head-end 101 receives a user request for content, thelocal infrastructure system manager 140 determines whether the requestedcontent selection is stored in the local storage medium 148 (shown inFIG. 1). If the requested content is not in the local storage medium148, the local infrastructure system manager 140 identifies a remotestream caching server 202 that stores the requested program content andthen provides a server request to the remote system manager 204. Inresponse to this server request, the remote stream caching server 202streams the requested program content over the stream distributionnetwork 104 to the local stream caching server 102.

For example, the system manager 140 at a local head end 101 located in afirst city may receive a request for a particular content selection. Ifthe content is not in the storage medium 148, the system manager 140coordinates the retrieval of the requested content from another remotelylocated server 202, such as a remote server 202 located in a secondcity. The content is streamed from the remote server 202 to the localserver 102 via the distribution network 104 and then streamed to thelocal access network of subscriber. If the manager 140 determines thereare enough user requests above some predetermined threshold number, thenthe retrieved content is also stored locally in the storage medium 148(shown in FIG. 1).

The manager 140 provides session management for streaming content inaccordance to the RTP Control Protocol (RTCP). Such management isparticularly important in the case of content streamed to the localstream caching server 102 from the remote server 202. If any errorsoccurred during the streaming from the remote server 202, these errorsare multiplied when the cached or stored content is subsequentlystreamed to the many subscribers. RTCP enables the detection andtransmission of only the read blocks affected by the streaming errors.Additionally, the manager 140 may selectively stream content (e.g., amovie) at off peak times, when the costs for bandwidth are lower thanpeak usage hours (e.g., after midnight). The content may be streamed asbetween two or more servers to facilitate local storage at varioushead-ends. Likewise, a requestor may preorder content and have thecontent downloaded to a subscriber's digital video recorder (DVR) atsuch low traffic times of the day. In this manner, bandwidth allocationis controlled by the infrastructure system manager 140 to improve thequality of service over the distribution system 100 and guaranteefidelity for DVR applications.

Another inventive aspect of the system 100 involves streaming of contentin real time. The server 102 continuously receives content from a remoteserver 202 and streams the received content in real time to a pluralityof subscriber terminals. Additionally, the server 102 may store andstream content that is preprocessed in accordance to the IP format. Suchpreprocessing is described in co-filed patent application entitled“Method and Apparatus For Preprocessing and Post Processing content inan Interactive Information Distribution System”, patent application Ser.No. 09/772,288, which is hereby incorporated herein by reference in itsentirety.

Furthermore, an application program such as a video player (e.g.,REALAUDIO™. REALVIDEO™, REALPLAYER™, and the like) may be stored at thehead-end 101 and streamed to a subscriber who is requesting content.Streaming such application program is much faster than having todownload such application program by using an FTP file or the like.Therefore, quality of control and operation from the perspective of thesubscriber is greatly improved. In addition, the subscriber equipment115 (e.g., a set-top box) does not have to store such applicationprogram permanently, since the application program can be quicklydownloaded from the stream server 102.

FIG. 6 depicts a flow diagram of a method 600 to respond to a requestfor a particular program content selection. A local stream cachingserver 102 may implement the method 600 upon executing the software 152by the CPU 146. Initially, the method 600 starts at step 602 andproceeds to step 604, where a request for a program content is receivedfrom subscriber equipment 115 such as a subscriber terminal. At step606, a query determines whether the requested program content isavailable from the stream caching server 102. Namely, step 606determines whether the requested program content is stored in thestorage medium 148.

If the requested program content is available from the stream cachingserver 102, the method 600 proceeds to step 608 where the IP formattedprogram content is retrieved from the storage medium 148. The retrievedcontent is streamed over the distribution network 104 at step 618. Afterthis streaming, the method 600 ends at step 626.

If the requested program content is not in the stream caching server102, the method 600 proceeds to step 610 where a query determineswhether the requested program content is in a remote streaming cachingserver 202. If the requested program content is not in any remotestreaming caching server 202 within the system 100, the method 600proceeds to step 624 to provide an error signal to the system manager140, and the method 600 ends at step 626. If the requested programcontent is present in a remote streaming caching stream server 202, thenin step 612, the method 600 retrieves the IP formatted program contentfrom the remote stream server 202.

The method 600 proceeds to step 614, where a query determines whetherthere is other demand for the requested program content retrieved fromthe remote stream server 202. Namely, in step 614, a the system manager140 determines whether there is enough interest in that program content,i.e., whether a threshold number of subscribers ordered or requestedthat program content. If there is no real demand, i.e., demand is belowa threshold level, then the method 600 proceeds to step 616 where theprogram content is simply received from the remote stream server 202.The method 600 proceeds to stream video over the distribution network at618 and ends at step 626.

If there is other demand for the requested program content, i.e., demandis above the threshold level, then the method 600 proceeds to stream theprogram content over the distribution network 104 at step 620 and storethe program content in the storage medium 148 at step 622. Thereafter,in step 618, the program content is streamed over the distributionnetwork 104 to the subscriber, and the method 600 ends in step 626.

FIG. 7 depicts a flow diagram of a method for adapting content delivery.Specifically, FIG. 7 depicts a flow diagram of a method 700 suitable foruse in the system 500 of FIG. 5 for delivering content to a client. Themethod 700 of FIG. 7 is entered at step 702 when an HTML page request isreceived from a subscriber.

At step 704, the requested page is created using either static and/ordynamic HTML pages and/or objects. At step 706, a request for an objectis received from the client. At step 708, the type of object requestedis identified. As shown in FIGS. 4 and 5, the requested object maycomprise one of a static object, a dynamic object, a streaming object,and the like.

At step 710, the resource associated with the requested object isrequested to be provided based on, for example, the Uniform ResourceLocator (URL) associated with the requested object. In the case of astatic HTML resource, a request is forwarded to the static HTML pageproxy server 502 of FIG. 5. In the case of a request associated with adynamic HTML page, a request is forwarded to the dynamic HTML pageserver 504. In the case of a request for streaming content, a request isforwarded to the stream caching server 102.

At step 712, the static and/or dynamic HTML information (includingrelated objects) is compiled. At step 714, static and/or dynamic HTMLinformation (including related objects) is transmitted to the requestingclient. The transmitted information is adapted to be processed by theclient to produce an image on, for example, a browser display screen. Itis noted that the displayed image may be divided into a plurality ofregions or frames, a plurality of objects, and the like.

At step 716, a streaming object requested at step 706 by the client, andrequested from the stream caching server 102 by controller 160 at thesystem manager 140, is streamed through the distribution network 104 tothe client, such that the client display image will show the streamedinformation in an appropriate object or frame. Thus, in the case of aclient selecting an object associated with video imagery and/or audioinformation, a client-side display object, such as a frame or otherimage region will be used to delineate an image area associated with thestreamed content. In this manner, the stream caching server 102, httpproxy server 502 and 504, as well as any other servers providing varioustypes of content (e.g., mail server, chat server, and the like) arecoordinated to provide to a client requested content in efficient andseamless manner, and in step 718, the method 700 ends.

Although various embodiments that incorporate the teachings of thepresent invention have been shown and described in detail herein, thoseskilled in the art can readily devise many other varied embodiments thatstill incorporate these teachings.

What is claimed is:
 1. A method comprising: transcoding, by a computingdevice, content data to a format supported by an access network,resulting in transcoded content data, wherein the computing device is incommunication with an interface device for the access network via adistribution network; encapsulating, by the computing device, thetranscoded content data, resulting in encapsulated content data that isin a format supported by the distribution network, wherein the formatsupported by the access network is different from the format supportedby the distribution network; and causing transmission, to the interfacedevice via the distribution network, of the encapsulated content data.2. The method of claim 1, wherein the format supported by thedistribution network comprises an Internet Protocol (IP) format.
 3. Themethod of claim 1, wherein the encapsulated content data comprises atleast one RTP packet.
 4. The method of claim 1, wherein the encapsulatedcontent data comprises at least one IP packet.
 5. The method of claim 1,wherein the encapsulated content data comprises at least one UserDatagram Protocol (UDP) packet.
 6. The method of claim 1, wherein thecontent data comprises video-on-demand content data.
 7. The method ofclaim 1, wherein the content data comprises pay-per-view content data.8. The method of claim 1, wherein the content data comprises digitalbroadcast content data.
 9. The method of claim 1, wherein the contentdata comprises encoded audio data.
 10. One or more non-transitorycomputer-readable media storing executable instructions that, whenexecuted, cause an apparatus to: transcode content data to a formatsupported by an access network, resulting in transcoded content data,wherein the apparatus is in communication with an interface device forthe access network via a distribution network; encapsulate thetranscoded content data, resulting in encapsulated content data that isin a format supported by the distribution network, wherein the formatsupported by the access network is different from the format supportedby the distribution network; and cause transmission, to the interfacedevice via the distribution network, of the encapsulated content data.11. The one or more non-transitory computer-readable media of claim 10,wherein the format supported by the distribution network comprises anInternet Protocol (IP) format.
 12. The one or more non-transitorycomputer-readable media of claim 10, wherein the content data comprisesvideo-on-demand content data.
 13. The one or more non-transitorycomputer-readable media of claim 10, wherein the content data comprisespay-per-view content data.
 14. The one or more non-transitorycomputer-readable media of claim 10, wherein the content data comprisesdigital broadcast content data.
 15. The one or more non-transitorycomputer-readable media of claim 10, wherein the content data comprisesencoded audio data.
 16. A system comprising: an interface device for anaccess network; and a computing device comprising: one or moreprocessors; and memory storing executable instructions that, whenexecuted by the one or more processors, cause the computing device to:transcode content data to a format supported by the access network,resulting in transcoded content data, wherein the computing device is incommunication with the interface device via a distribution network;encapsulate the transcoded content data, resulting in encapsulatedcontent data that is in a format supported by the distribution network,wherein the format supported by the access network is different from theformat supported by the distribution network; and cause transmission, tothe interface device via the distribution network, of the encapsulatedcontent data.
 17. The system of claim 16, wherein the content datacomprises video-on-demand content data.
 18. The system of claim 16,wherein the content data comprises pay-per-view content data.
 19. Thesystem of claim 16, wherein the content data comprises digital broadcastcontent data.
 20. The system of claim 16, wherein the content datacomprises encoded audio data.